The present invention pertains to a duplex structure signal transfer point system for common channel signalling system No. 7 suggested by CCITT (International Telegraph and Telephone Consultative Committee).
Unit level 2, one of the units which accept protocol for message transfer, is a board that runs protocol level 2 of the message transfer part protocol. Unit level 3 is a board that runs message handling protocol, which governs message routing in protocol level 3 of the message transfer protocol. Network level 2--3 interconnects the units such as a unit level 3, a network unit level 3--3, and many unit level 2's And a signal message processing sub-module, comprising the unit level 3, the unit level 2, and the network unit level 3--3, is constructed by interconnection of each unit with a network unit 2--3.
In prior art signal transfer point systems, a network level 2--3 with only one path is used for the interconnection between the unit level 3 and the unit level 2's. Also, a network level 3--3 with one path is used for the interconnection between such modules. In cases a path is malfunctioning, many unit level 2's or modules are disabled given that there's just one path in such a system.